通知没有出现？

Question

我有这个通知：

private void sendSimpleNotification(){ 

    boolean permanent = PreferenceManager.getDefaultSharedPreferences(context).getBoolean("permanent", false);

    if(permanent) {
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(service.this);
        notificationBuilder.setContentTitle("Title");
        notificationBuilder.setContentText("Context");
        notificationBuilder.setTicker("TickerText");
        notificationBuilder.setWhen(System.currentTimeMillis());
        notificationBuilder.setSmallIcon(R.drawable.ic_stat_icon);

        Intent notificationIntent = new Intent(this, service.class);
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0, notificationIntent, 0);

        notificationBuilder.setContentIntent(contentIntent);
        notificationBuilder.setDefaults(Notification.DEFAULT_SOUND | Notification.DEFAULT_LIGHTS | Notification.DEFAULT_VIBRATE);
        mNotificationManager.notify(1, notificationBuilder.build());
    } 
    else{
        mNotificationManager.cancel(SIMPLE_NOTIFICATION_ID);      
    }

}

我的目标是，当选中checkboxpreferences时，会显示通知，否则取消选中消息。但是当选中/取消选中首选项屏幕中的复选框时，出现错误并且通知不会显示/消失。我可以在某个地方拨打sendSimpleNotification吗？我不知道错误在哪里。